Cutting tools having rotating cutting inserts are known in the art. U.S. Pat. Nos. 4,621,955 and 4,477,211, both issued to Leonard A. Briese, show cutting tools having rotating cutting inserts. The inserts in each of the Briese patents are generally cylindrical and are mounted for rotation about a central axis. In use, the forces acting on the insert as the insert cuts through a workpiece cause the insert to rotate about its central axis. The rotation of the insert continually changes the cutting edge of the insert which is in contact with the workpiece resulting in longer insert life and lower cutting forces.
A U.S. Patent Application entitled Metal Boring With Self-Propelled Rotary Inserts was filed in the U.S. Patent Office on Mar. 4, 1998, and was assigned to Rotary Technologies Corporation. That application describes a boring tool with rotary cutting inserts in which the inserts are symmetrically mounted in the tool with respect to the boring tool axis. It has been determined that improved results can be obtained by mounting the rotary cutting inserts in a boring tool so that the inserts are non-symmetrically mounted and staggered with respect to the axis of the tool.